Drinking water quality · 2025
· Verified
What's in City of Antioch, CA tap water
101 contaminants were measured in the City of Antioch, CA water system's 2025 annual report. Each is shown below against its federal limit — 3 sit at or above that limit.
- Reporting year
- 2025
- Contaminants measured
- 101
- Over federal limit
- 3
- Approaching the limit
- 0
- Worst contaminant
- Turbidity
- Service area
- CA
1.9× the limit
state-level CCR
Where your water comes from · EPA SDWIS
City of Antioch, CA's drinking water comes from surface water, drawn from 2 sources.
Source
2surface water
- ANTIOCH MUNICIPAL RESERVOIR
- SAN JOAQUIN RIVER INTAKE
Treatment
1treatment plant
- ANTIOCH WTP
Distribution
0storage units
Also buys water from CONTRA COSTA WATER DISTRICT, RANDALL-BOLD WATER TREATMENT PLANT, and 2 more.
Source: EPA SDWIS facilities inventory. Methodology.
Historical readings · EPA Six-Year Review (2012–2019)
1 contaminant historically over EPA limits in City of Antioch, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
BROMATE worst: 2014 | 0.01 mg/L 1.0× | 0.01 mg/L | '13'14'17 |
TTHM worst: 2018 | 0.074 mg/L 93% | 0.08 mg/L | '12'13'14'16'17'18'19 |
DICHLOROMETHANE worst: 2017 | 0.0034 mg/L within | 0.005 mg/L | '17 |
ARSENIC worst: 2013 | 0.0047 mg/L within below national p90 | 0.01 mg/L | '12'13'14'15'16'17'18'19 |
CADMIUM worst: 2017 | 0.0016 mg/L within near national p90 | 0.005 mg/L | '17 |
FLUORIDE worst: 2012 | 0.95 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
HAA5 worst: 2017 | 0.0088 mg/L within | 0.06 mg/L | '12'13'14'16'17 |
NITRATE worst: 2013 | 0.994 mg/L within | 10 mg/L | '12'13'14'15'16'17'18'19 |
BARIUM worst: 2012 | 0.16 mg/L within near national p90 | 2 mg/L | '12'16'17'18'19 |
NITRATE NITRITE worst: 2017 | 0.72 mg/L within | 10 mg/L | '16'17'18'19 |
DEHP worst: 2019 | 0.00028 mg/L within | 0.006 mg/L | '19 |
CYANIDE worst: 2018 | 0.0011 mg/L within below national p90 | 0.2 mg/L | '18'19 |
DEHA worst: 2019 | 0.00021 mg/L within | 0.4 mg/L | '19 |
COPPER worst: 2019 | 0.32 mg/L below national p90 | — | '19 |
LEAD worst: 2019 | 0.0028 mg/L | — | '19 |
DBAA worst: 2012 | 0.0029 mg/L | — | '12'13'14'16'17 |
DCAA worst: 2012 | 0.0026 mg/L | — | '12'13'14'16'17 |
MBAA worst: 2016 | 0.0026 mg/L | — | '16 |
TCAA worst: 2017 | 0.0042 mg/L | — | '17 |
BROMODICHLOROMETHANE worst: 2012 | 0.0053 mg/L | — | '12'13'14'16'17'18'19 |
BROMOFORM worst: 2012 | 0.0076 mg/L | — | '12'13'14'16'17'18'19 |
CHLOROFORM worst: 2012 | 0.0029 mg/L | — | '12'13'14'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.0079 mg/L | — | '12'13'14'16'17'18'19 |
PWSID CA0710001 · Source: EPA Six-Year Review 4 (2012–2019). Values are the highest detection in each calendar year; non-detect years are omitted. Year tags above show every year with a detection.
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TurbidityA measure of cloudiness from suspended particles in the water. | 9.4 NTUAverageSource water | 5 NTUMCL | At or above the limit |
| ColorA measure of visible tint in the water. | 15 UNITSAverageSource water | 15 UNITSMCL | At or above the limit |
| OdorA measure of detectable smell in the water. | 1.25 TONAverageEntry point | 3 TONMCL | Within the limit |
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 460 UMHO/CMAverageSource water | 1600 UMHO/CMMCL | Within the limit |
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 260 MG/LAverageSource water | 1000 MG/LMCL | Within the limit |
| AlkalinityA measure of the water's capacity to neutralize acids. | 44.699999999999996 MG/LAverageSource water | None set | Detected — no federal limit |
| HardnessA measure of dissolved calcium and magnesium minerals. | 78 MG/LAverageSource water | None set | Detected — no federal limit |
| pHA measure of how acidic or basic the water is. | 8.35 PHAverageEntry point | None set | Detected — no federal limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| IronA naturally occurring metal common in groundwater. | 510 UG/LAverageSource water | 300 UG/LMCL | At or above the limit |
| ManganeseA naturally occurring metal from soil and rock. | 22 UG/LAverageSource water | 50 UG/LMCL | Within the limit |
| AluminumA common element sometimes used as a treatment coagulant. | 400 UG/LAverageSource water | 1000 UG/LMCL | Within the limit |
| NickelA metal from natural deposits and industrial discharge. | 2 UG/LAverageSource water | 100 UG/LMCL | Within the limit |
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.11 UG/LAverageSource water | 10 UG/LMCL | Within the limit |
| ZincA naturally occurring metal that can also enter water from corroding pipes. | 19 UG/LAverageSource water | 5000 UG/LMCL | Within the limit |
| Antimony | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Beryllium | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| MercuryA toxic metal from erosion of natural deposits and industrial runoff. | Not detected UG/LHighest single sampleEntry point | 2 UG/LMCL | None detected |
| SeleniumA trace element from natural deposits and industrial discharge. | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| Thallium | Not detected UG/LHighest single sampleSource water | 2 UG/LMCL | None detected |
| CalciumA naturally occurring mineral that contributes to water hardness. | 8.25 MG/LAverageEntry point | None set | Detected — no federal limit |
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 11 MG/LAverageSource water | None set | Detected — no federal limit |
| PotassiumA naturally occurring mineral from rock and soil. | 2.8 MG/LAverageSource water | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 54 MG/LAverageSource water | None set | Detected — no federal limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorideA naturally occurring salt compound. | 92 MG/LAverageSource water | 500 MG/LMCL | Within the limit |
| SulfateA naturally occurring mineral from rock and soil. | 31.5 MG/LAverageEntry point | 500 MG/LMCL | Within the limit |
| NitriteA compound from fertilizer runoff, sewage, and erosion of natural deposits. | Not detected MG/LHighest single sampleEntry point | 1 MG/LMCL | None detected |
| Ammonia | 0.66 MG/LAverageEntry point | None set | Detected — no federal limit |
| BromideA naturally occurring salt found in source water. | 0.13 MG/LAverageEntry point | None set | Detected — no federal limit |
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | 2.59 PCI/LAverageEntry point | 15 PCI/LMCL | Within the limit |
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chromium | 1.2 UG/LAverageSource water | 50 UG/LMCL | Within the limit |
| Carbofuran | Not detected UG/LHighest single sampleSource water | 18 UG/LMCL | None detected |
| Carbon Tetrachloride | Not detected UG/LHighest single sampleEntry point | 0.5 UG/LMCL | None detected |
| Chlordane | Not detected UG/LHighest single sampleSource water | 0.1 UG/LMCL | None detected |
| Chlorobenzene | Not detected UG/LHighest single sampleEntry point | 70 UG/LMCL | None detected |
| Cis Dichloroethylene 12 | Not detected UG/LHighest single sampleEntry point | 6 UG/LMCL | None detected |
| Dichloroethane 12 | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Dichloroethylene 11 | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Dichloropropane 12 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Dinoseb | Not detected UG/LHighest single sampleSource water | 7 UG/LMCL | None detected |
| Diquat | Not detected UG/LHighest single sampleSource water | 20 UG/LMCL | None detected |
| Edb | Not detected UG/LHighest single sampleSource water | 0.05 UG/LMCL | None detected |
| Endothall | Not detected UG/LHighest single sampleEntry point | 100 UG/LMCL | None detected |
| Endrin | Not detected UG/LHighest single sampleSource water | 2 UG/LMCL | None detected |
| Glyphosate | Not detected UG/LHighest single sampleEntry point | 700 UG/LMCL | None detected |
| Heptachlor | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Heptachlor Epoxide | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Hexachlorobenzene | Not detected UG/LHighest single sampleEntry point | 1 UG/LMCL | None detected |
| Hexachlorocyclopentadiene | Not detected UG/LHighest single sampleEntry point | 50 UG/LMCL | None detected |
| Mcaa | Not detected UG/LHighest single sampleDistribution | None set | None detected |
| Methoxychlor | Not detected UG/LHighest single sampleEntry point | 30 UG/LMCL | None detected |
| O Dichlorobenzene | Not detected UG/LHighest single sampleSource water | 600 UG/LMCL | None detected |
| Oxamyl | Not detected UG/LHighest single sampleEntry point | 50 UG/LMCL | None detected |
| P Dichlorobenzene | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Pcb Total | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Pce | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| Pentachlorophenol | Not detected UG/LHighest single sampleEntry point | 1 UG/LMCL | None detected |
| Picloram | Not detected UG/LHighest single sampleSource water | 500 UG/LMCL | None detected |
| Styrene | Not detected UG/LHighest single sampleSource water | 100 UG/LMCL | None detected |
| Tce | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| Toxaphene | Not detected UG/LHighest single sampleEntry point | 3 UG/LMCL | None detected |
| Trans Dichloroethylene 12 | Not detected UG/LHighest single sampleSource water | 10 UG/LMCL | None detected |
| Trichlorobenzene 124 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Trichloroethane 111 | Not detected UG/LHighest single sampleSource water | 200 UG/LMCL | None detected |
| Trichloroethane 112 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Twofourd | Not detected UG/LHighest single sampleEntry point | 70 UG/LMCL | None detected |
| Vinyl Chloride | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| PerchlorateA chemical used in rocket fuel and fireworks that can also form during disinfection. | Not detected UG/LHighest single sampleEntry point | 6 UG/LMCL | None detected |
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 1,2,3-TCP | Not detected UG/LHighest single sampleSource water | 0.005 UG/LMCL | None detected |
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Benzene | Not detected UG/LHighest single sampleEntry point | 1 UG/LMCL | None detected |
| Benzo(a)pyrene | Not detected UG/LHighest single sampleSource water | 0.2 UG/LMCL | None detected |
| ChloroethaneA volatile organic compound used in some industrial processes. | Not detected UG/LHighest single sampleEntry point | None set | None detected |
| Chloromethane | Not detected UG/LHighest single sampleEntry point | None set | None detected |
| Dalapon | Not detected UG/LHighest single sampleEntry point | 200 UG/LMCL | None detected |
| Dichlorodifluoromethane | Not detected UG/LHighest single sampleSource water | None set | None detected |
| Ethylbenzene | Not detected UG/LHighest single sampleEntry point | 300 UG/LMCL | None detected |
| Simazine | Not detected UG/LHighest single sampleEntry point | 4 UG/LMCL | None detected |
| Toluene | Not detected UG/LHighest single sampleSource water | 150 UG/LMCL | None detected |
| XylenesA group of industrial solvents found in gasoline and paint. | Not detected UG/LHighest single sampleEntry point | 1750 UG/LMCL | None detected |
Source: City of Antioch, CA's 2025 Consumer Confidence Report — the annual drinking-water report every U.S. utility is required to publish. The numbers on this page are the utility's own. A water-quality report covers an entire service area, not a single address.
People also ask about City of Antioch, CA's water
+Is City of Antioch, CA tap water safe to drink in 2025?
The 2025 Consumer Confidence Report for the City of Antioch, CA water utility lists 3 contaminants at or above the federal limit: Turbidity, Iron, and Color. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in City of Antioch, CA tap water?
101 contaminants were measured in City of Antioch, CA's 2025 Consumer Confidence Report, spanning other, metals, and vocs & pesticides. 80 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in City of Antioch, CA tap water?
3 contaminants in City of Antioch, CA's 2025 report sit at or above the federal limit: Turbidity (1.9× the limit); Iron (1.7× the limit); Color (1.0× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in City of Antioch, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2025 report is Turbidity, at 1.9× the federal threshold. It belongs to the physical & aggregate family of contaminants.
+Where does the data on this page come from?
Every value is transcribed from City of Antioch, CA's 2025 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is City of Antioch, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2025 report; a new report will replace it once the utility publishes its next annual update.
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